Field of Disclosure
This disclosure relates to an inorganic oxide pigment, and in particular to titanium dioxide pigment, TiO2, suitable for use in polymer compositions.
Description of the Related Art
High molecular weight polymers, for example, hydrocarbon polymers and polyamides, are melt extruded into shaped structures such as tubing, pipe, wire coating or film by well-known procedures wherein a rotating screw pushes a viscous polymer melt through an extruder barrel into a die in which the polymer is shaped to the desired form, and is then subsequently cooled and solidified into a product, that is, the extrudate, having the general shape of the die. In film blowing processes, as an extruded plastic tube emerges from the die the tube is continuously inflated by air, cooled, collapsed by rolls and wound up on subsequent rolls.
Inorganic powders are added to the polymers. In particular, titanium dioxide pigments are added to polymers for imparting whiteness and/or opacity to the finished article. To deliver other properties to the molded part or film, additional additives are incorporated into the processing step. What is needed is a titanium dioxide that has multiple properties associated with it.
A typical method for combining inorganic pigment particles and polymers utilizes dropping the pigment and polymer through a feed tube into the feed barrel or into the side stuffer of an extruder from which is it then compounded. Alternatively, the inorganic particles can be dropped with the polymer into the cavity of a rotational blender such as a Banbury.
A need exists for a process for the addition of silica, alumina and zinc oxide to the titanium dioxide pigments that provides improved photostability and reduced microbial activity.